by Robert C. Moler

Originally published in The Stellar Sentinel,
Newsletter of the Grand Traverse Astronomical Society, June 2018

The
planet Mars has oppositions from the Sun about every 26 months more
or less. These oppositions are a time when Mars is closest to the
Earth for its position in orbit. It’s distance at these times
range from 34.6 to almost
63 million miles, a range of almost 2 to 1. This is because Mars has
a very elliptical orbit as can be seen in the illustration on page 2.

Especially
close approaches to the
Earth occur every
15 or 17 years in the
latter half of summer in those years.
My first close approach
was September 7, 1956. It was a famous one for the time.
Professional astronomers of that time were pretty sure that
Mars didn’t have canals, features
that were
‘discovered’ by Giovanni Schiaparelli in
1877. To him the features were grooves or channels. Unfortunately
the Italian word for them was canali. The
world press proclaimed that there were “canals” on Mars.
Canals by definition are artificial and require canal builders,
Martians by inference.

Like
I said, professional astronomers had
discounted them by 1956.
But science fiction read by young impressionable amateur astronomers
like myself
talked about old races of Martians hoarding every last drop of
water. So maybe we believed. With my 5 inch reflector I observed
the polar cap and the large
dark feature Syrtis Major.

My
next close approach of
Mars was August 12, 1971. That summer I was working out of town and
in the midst of a move from Grand Rapids to Traverse City, so was
unable to observe Mars properly.

In
the summer and autumn of 1973 I was able to do an observing program
of Mars when it was almost
as close as in 1971,
drawing its features. I found out that to really
observe a planet it takes time to educate the eye and brain to see
faint, fuzzy detail. And since I didn’t believe in canals by
this time, I didn’t see them.

The
next close approach was
September 22, 1988. The first “Mars Night” held by the
society. We had a great turnout. But Mars was tiny as seen in
telescopes. At best it was 23.81 seconds of arc in diameter. The
Moon and Sun are about 1,800 seconds in diameter. It would be a bit
larger than half the apparent diameter of Jupiter at average
distance.

On
August 27, 2003 Mars came closer than at any time in 50,000 years
some astronomers said. The society held its second “Mars
Night” at the Rogers Observatory, and wow, the lines of people
ran down the drive and onto the shoulder of the road. As in 1988, I
was stationed on the lawn at the front of the observatory with the
portable Celestron 11 telescope, which actually gave clearer views
than the 14 inch telescope in the dome. (Hot bodies in dome make for
lousy seeing.)

2003
is also memorable or rather infamous for the “Mars Hoax”
email. Proclaiming that Mars would appear as large as the Moon on
August 27th.
This hoax has been propagated every two years since. I expect 2018
to be a banner year for the resurrection of the hoax.

We
come to this year, 2018, 15 years after the 2003 closest approach.
Mars will reach opposition on July 27th.
It’s closest approach to the Earth will be on July 31st,
at the distance of 35,784,000
miles. The reason the dates aren’t the same is that Mars will
still be a month before reaching perihelion, its closest to the Sun,
so it’s getting even
closer than
at the time of opposition.

The
Mars oppositions
of October 2020, December 2022, January 2025 and February 2027 will
be of increasing distances up
to 63.0 million miles. This will be followed
by oppositions of decreasing
distances in March 2029,
May 2031, and July 2033 leading to another close approach on
September 11, 3035 at 35.4
million miles.

However
by 2035 there may be humans on Mars waving back at us. It’s
odd that anyone on Mars at the time probably wouldn’t be able
to see the Earth at that time. Martian oppositions for us, are the
time of inferior conjunctions of Earth with the Sun. We’d be
lost in the Sun’s glare.

For
the very closest views of Mars get on the Internet and search for
Mars Curiosity,
Mars Opportunity
and Mars Hirise.
No
telescope required.